Lubricant and method of producing same



a Patented July, 27, 1937 UNITED STATES PATENT OFFICE 2,088,193LUBRICANT AND METHOD or PRODUCING smvm William L. Evers, Woodbury, J.,as'signor to Socony-Vacuum Oil Company, Incorporated,

New York, N. Y., a corporation of New York Application February 27,1935, Serial No. 8,554

No Drawing.

'7 Claims.

1o Extreme.pressur e lubricants mustbe capable of withstanding extremelyhigh unit loading. Typical applications are the lubrication of freewheeling devices, certain: forms of ball-bearing power transmissiondeviceacertain forms of gear tooth characterized byhigh tooth pressure,metal cuttin and similar instances. Extreme pressure,

, lubricants are usually compounded from oils of 4 high viscosity andtheoil plays some part in the lubrication, although' the major portion ofthe effectiveness is because of the presence of a characterlzingingredient. Ingredients for lubricants of these types-havebeen ofvarious forms. This invention has to do specifically with novelingredients of this nature and their method of 5 manufacture, theinvention contemplating the ingredient alone or in combination withother 1 ingredients to form the active portion of lubricents for theabove indicated use, andthe complete lubricant. i

It is an object of this invention to produce a.

novel and valuable base for such lubricants, to prepare such a basehaving good characteristics of stability, and to provide means for "thepreparation of such'ingredients. A further object is the preparation ofextreme pressure lubricants characterized by the presence of theseingredients. alone or in combination'with other ingredients.Further-objects are theprovision of methods of preparing lubricants andsuch other objects and 4 advantagesias' may hereinafter appear.

"Hie preparation of the novel ingredients fo extreme pressure lubricantsin acccruan e w t this *lave ea s efl tad first interactin a;

n ercaptide or'mercaptides' with one or mo'fe halogen-substitutedfatty'acidsfor alkali .inetal-salt,

or'saltsf thereof, or otherhi'etallic salts thereof mam-e whi h the m anid reaction. 101- 1 preraratioagpta r action-product. 1mm niercaptosubstituted fatty.-acidg and low b stannic chloride. Chlor-substituted'fatty acids are preferred. The preferred range of fatty acids is frombutyric to caprylic, inclusive. The first step of the process justmentioned produces a new composition of the general formula RS CH2 XCOOH5 where R. is any alkyl or aryl radical. If a metal salt of the fattyacid is used, the reaction product will be of the general formulaRS(CH2)XCOOM, where M is the metal. The M is displaced with H byacidifying the solution, as with hydrochloric or sulfmic acid. Thenstapnic chloride may be incorporated with the above resulting organicacid. The product of this second reaction has been found to exhibitnovel and characteristic ability for imparting load bearing capabilitiesto hydrocarbon lubricants, together with an unusual stability and otherdesirable qualifications for such purpose.

As an example of the preparation of one of these novel ingredients, Imaycitethe following: Chloracet'ic'acid (CICHzCOOH) maybe converted to itssodium salt, for example, by dissolving in a caustic soda solution, and.this sodium salt reacted with a sodium mercaptide or a mixtude of sodiummercaptides typified by the general formula RSNa where R indicates anyalkyl or aryl radical. This reaction is capable of proceeding under itsown heat of reaction,-but I prefer to apply heat sufflcient to maintaina temperature in the range 30 of to C. in-order to obtain high yields.For maximum yield the fatty acid and mercaptide should be reacted instoichiometric proportions, altho this is not essential-"to the purposesof this invention. After completion of this first re- .action, thereaction mixture is introduced into acidified water whichdzakes out anysalt, sodium or unreacted chloracetic acid, and also reacts with. thesodium salt which is the first reaction product; theoily reactionproduct of the second: reaction separates as a top layer, is taken upwith ether, and any unreacted-merfcaptan removed by distillatiomleavingthe desired second reaction product. The product obtained from theprocess; atithis stage of reaction is an oily substanceIg which may betypified bythe formula to 30%, for example about 10% by weight ofstannic chloride, not in such large amount as to separate out when thefinished product is mixed into mineral lubricating oil at roomtemperature. This second reaction is also exothermic. I have found thatit usually results at first in the formation of a white precipitatewhich subsequently dissolves. No evolution of hydrochloric acid gas isobserved. The resultant compound is probably (RSCH2COOH)2SI1C14 [or, forany fatty acid the general formula will be (RS (CH2) XCOOH)2S1'1C14], ina solution of mercapto acid and/or an excess of stannic chloride. Theformation of a precipitate and evolution of heat point to the formationof an addition compound. However, it is not certain that the finalcompound attained is of this type, and for purposes of definition, Ichoose to indicate my final product, which is the subject matter of thisinvention, as the reaction product of stannic chloride and a mercaptancontaining organic acid. This compound, I have found to be capable ofserving as a characterizing ingredient in extreme pressure lubricants toenable them to withstand high unit loading. In the formation of mypreferred compound, I prefer to incorporate about 10% stannic chloridewith the mercaptan-containing organic acid. The particular halide alsomay be iodine or bromine as well as chlorine, insofar as these otherhalides form substituted acids capable of performing reactions of thistype. Mixed mercaptides and mixed metal salts of fatty acids can beused, and it is not necessary that the metal of the mercaptide and themetal of the salt be the same.

As an example of the efficacy of this novel ingredient, I cite belowtests wherein an extreme pressure lubricant compounded with this novelingredient was directly compared with a mineral lubricating oil (column2) and with this oil containing stannic chloride (column 3). Oils of thetype referred to herein may be tested upon the Almen pin test machine,described by Moughey and Almen, (Proc. A. P. I. 1931, page 77), whereina pin is rotated in bearings so designed that increasing pressures maybe applied to the lubricated surface. This machine is widely used insuch comparative evaluations. In the following tabulation of resultsfrom the Almen pin test machine, the first column is the pressure inpounds per square inch applied to the lubricated contact surfaces.Columns 2, 3, 4 and 5 show the torque transmitted through the pin of thetest machine, and show the pressure at which lubrication failed,resulting in seizure of the surfaces of the bearing and pin.

Table Pressure Torque Transmitted Foot-pounds lOil Pounds per a on plusOil plus 0.17 Oil plus 2.0

sq. inch 0.1% $116!; new base new base IIIIIIIIIIIII "6.75

6. 3 Seized.

In the tabulation given aboveQthe oil used in column 2 was a cylinderstock havinga viscosity of about 165 seconds Saybolt at 210 F. This oilis an oil of the type normally used in the compounding of extremepressure lubricants, and in the absence of special characterizingingredients, may be used for such services, altho it is quite in--eifective. The oil whose tests are reported in column 3, consists of thesame oil as in column 2, containing of 1% by weight of stannic chloride,which has a moderate capability alone as an E. P. ingredient, and thisamount of stannic chloride is comparable with the amount of stannicchloride in an E. P. lubricant compounded with 1% of the novel baseherein described. It will be observed that the oil of column 3 failed ata pressure of 8,000 pounds per square inch. Columns 4 and 5 show thetests of an E. P. lubricant composed of the oil of column 2 andcontaining 1% and 2% respectively of the novel characterizing ingredientherein described. It will be observed that the oils of columns 4 and 5lubricated without seizure to loads far in excess of those at whichfailure was had with the hydrocarbon oil alone or with the hydrocarbonoil and an amount of stannic chloride corresponding to that present inthe oil of column 4. The specific characterizing ingredient employed inthe oil of column 4 was prepared by incorporating stanic chloride with(iso-amyl) -SCH2COOH made from a pure mercaptide; the base used incompounding the oil of column 5 differed in that the originalmercaptan-containing acid was prepared by use of a mixture of mercaptansboiling in the range of 100 to 135 C. Whether the product is made frompure or mixed mercaptides is immaterial to the effectiveness of thefinished product, and whether the finished product contains 1% or 2% ofthe ingredient likewise makes little diiference.

In the claims, the term extreme pressure lubricating composition meanseither (and includes all) the finished lubricant as actually used, thecharacterizing extreme pressure ingredient itself, or any intermediateextreme pressure lubricant base, admixture or dilution containing theactive ingredient. The term mercaptan-substituted fatty acid", as usedin the claims, means the intermediate reaction product derived from thereaction between a mercaptide or mercaptides and a fatty acid or fattyacids, or metal salts thereof, within the scope of the detaileddefinitions given herein, said compound being of the general formulaRS(CH:)xCOOH. The term mercaptide as used in the claims means anymercaptide or mixture of mercaptides; similarly the terms "fatty acidand metal salt include both single and mixed fatty acids and salts.

I claim:

1. An extreme pressure lubricating composition comprising hydrocarbonlubricating oil and a minor proportion of the reaction product ofmercaptan-substituted fatty acid and stannic chloride.

2. A lubricant consisting mainly of relatively viscous hydrocarbonlubricating oil and a small I amount of a reaction product ofmercaptan-sube product calculated upon the weight of the hydro- .toincrease the load-bearing capacity or a product carbon all present inthe finished lubricant.

4. An extreme pressure lubricating composition comprising hydrocarbonlubricating oil and a minor proportion of the reaction product ofmercaptan-substituted fatty acid selected from the group consisting ofbutyric acid to caprylic acid,

inclusive.

5. An extreme pressure lubricating composition comprising a relativelyviscous hydrocarbon lubricating oil and a minor proportion, suilicientto increase the load-bearing capacity, 01' a product secured by reactinga mercaptide and an alkali metal salt oi a halogen substituted fattyacid to obtain a reaction product of the nature of a salt of amercapto-acid, acidifying this salt to recover therefrom the saidmercaptan-substituted fatty acid, and then reacting this acid withstannic.

chloride to obtain an active extreme pressure lubricating ingredient.

6. An extreme pressure lubricating composition comprising a majorproportionoi a hydrocarbon lubricating oil and a minor proportion,suilicient prepared by reacting a mercaptide with at least one compoundselected from the group consisting of elder-substituted fatty acids andalkali metal salts thereof, acidulating the iirst reaction product torecover a mercaptan-substituted fatty acid, and reacting this acid withstannic chloride to obtain an active extreme pressure ingredient.

'1. An extreme pressure lubricating composition comprising a majorproportion of a viscous hydrocarbon oil and a minor proportion,sufllcient to increase the load-bearing capacity 0! the mixture, of aproduct prepared by reacting a mercaptide with at least one compoundselected from the group consistsing of chlor-substituted fatty acidsfrom butyric to caprylic, inclusive, and alkali metal salts thereof,acidulating the first reaction product to obtain a mercaptan-substitutedfatty acid, and reacting this acid with stannic chloride to obtain thedesired characterizing ingredient.

WILLIAM L. EVERS.

